Proposal: Configurable Webhook Authorizer

[longquanzheng]

Is your feature request related to a problem? Please describe.
As of #2833 , Cadence has a AuthN interface and already plumbed through the system. However, it requires users to implement the interface and then re-compile the binary to use. This is not convenient because users have to be familiar with Cadence code base to make code change, and they will not be able to use the standard docker image from releases. Moreover, they have to keep their code in sync with Cadence.

Proposed Solution
Provide a configurable Webhook Authorizer via REST/HTTPS to external service, to determine if a request has enough permission.
Example as pointed out in the issue: https://kubernetes.io/docs/reference/access-authn-authz/webhook/ and

Additional context
N/A

[longquanzheng]

https://docs.google.com/document/d/1FlcI5UYk1hOyXe7WHMAjeh0fJCxPfXTiOKKRxuDVZ2I/edit#heading=h.nv1lcmmbd08i

[longquanzheng]

replaced by #4099